1. Field of the Invention
The invention relates to a contact tube for a welding torch, having a longitudinal axis, along which a continuous opening is provided for guiding a welding wire from an inlet area to an outlet area and from an outlet opening in the direction of a workpiece, at least one slot being provided in the outlet area for contacting the welding wire.
All supplementary materials for greatly varying welding methods are included under the term welding wire.
2. Description of the Related Art
Manifold contact tubes for welding torches are known from the prior art, which are provided with at least one slot in the area of the outlet opening for the welding wire. In this way, the contact tube becomes flexible in the area of the at least one slot, so that the diameter of the outlet opening can be reduced. A contact force can thus be exerted for contacting the welding wire. Various methods are known for achieving this contact force.
For example, a contact tube for a welding torch, which is provided with two slots, is known from EP 1 266 714 A1. The opening for conveying the welding wire is constricted with the aid of a ring, which is pushed over the contact tube in the area of the slots. It is disadvantageous in this case that no readjustment of the contact force is possible, and the outlet opening is expanded again by the resulting abrasion of the welding wire in the contact tube and the set contact force thus can no longer be maintained.
A contact tube for a welding torch is also known from U.S. Pat. No. 6,710,300 B2, by which the contacting of a welding wire is to be improved. This is performed in particular by exerting a contact force on the welding wire, in that a part of the contact tube which is provided with two slots is pressed using a spring against a fixed body. It is disadvantageous in this case that the mobility is restricted by the resistance on the fixed body, so that the contact force on the welding wire can only be set to a limited extent and increased abrasion of the welding wire is caused. Furthermore, the replacement of the contact tube is connected with an increased time expenditure, since additional connections of elements to the contact tube must be detached.
JP 2004001088 A and WO 2008/018594 A1 describe contact tubes for welding torches, which have, in addition to the slot which runs in the longitudinal direction, vertically situated slots in the outlet area of the welding wire, by which an adaptation of the contact tube to the welding wire can be improved.